When providing a hierarchical output_directory value like
'transient/jenkins-slave', the VM would fail to build in the CreateDisk
step.  The properly created output directory would not match the location
provided to CreateDisk, since datastorePath() did not properly split such
paths.  Now this case works; tested hierarchical and singular
output_directory values.

Migrate to new AWS repo

Fail the build when go vet returns non-zero exit code

Support force option for docker-tag.

Interpolate the "push" config

Add template_dir for path to template [GH-54]

Docker bug fixes

Merge branch 'docker-exec-by-version' of https://github.com/donaldguy/packer into donaldguy-docker-exec-by-version